A) The estimated total expense is
.. $600 +300 +200 +100 +200 = $1400
b) The estimated remaining to be saved is
.. $1400 -800 = $600
Undo what has been done to the variable. That means to do the opposite done to the variable.
5x-4=-19
+4=+4
5x=-15
5 is being multiplied to the variable so you divide it from both sides.
x=-3
Y = -3x + 13
Steps and the graph are on paper